A top secret federal court order reveals that the FBI and the National Security Agency are collecting the cell phone data of millions of Americans. The document, obtained by The Guardian, compels Verizon to send the NSA information about all telephone calls made on the telecom’s network within the United States. Here are seven quick things to know about the secret directive and its implications:

1. What Verizon Shares with the NSA: The court order requires Verizon to provide both the ingoing and outgoing telephone numbers of a given call, unique identifiers of individual phones, the time of the call and its duration. Subscribers’ names, addresses and contact information are not revealed. Calls and texts are also not monitored under the order.

2. Collecting Massive Amounts of Cell Phone Data is Legal, For Now: According to the court, information like phone numbers and call duration is considered “metadata” and can therefore be acquired by government agencies without individual warrants. The court order was signed by Roger Vinson, a federal judge in the U.S. Foreign Intelligence Surveillance Court and a U.S. District Court judge in northern Florida.

3. But Telling Americans That Their Data is Being Collected Isn’t Legal: The order specifically forbids Verizon from informing customers (or anyone else) that their data is being collected, stating “no person shall disclose to any other person that the FBI or the NSA has sought or obtained tangible things under this Order.”

4. The Government Has Done This Before: In 2006 USA Today reported that the NSA had a similarly expansive database of cellular data, not only from Verizon but also from AT&T and BellSouth. That program was launched as part of the push for tighter security and surveillance in the aftermath of the September 11 terrorist attacks. Despite public uproar and several lawsuits against cell phone carriers following the revelation, the NSA never officially announced that the database was shut down. The Electronic Frontier Foundation, a lobbying group that promotes digital privacy, still has pending litigation seeking to curtail the NSA’s practices.

5. The Current Data Collection Could Involve Other Carriers: Though the court order obtained by The Guardian only applies to Verizon, the Bush-era NSA database involved multiple carriers. Companies like Verizon have felt increasing pressure to provide customer data to government agencies in recent years. Cell phone carriers responded to 1.3 million requests for subscriber information from law enforcement agencies in 2011, according to The New York Times.

6. The Verizon Call You Make Today Could End Up in This Database: The court order went into effect on April 25 and runs until July 19.

7. The Guardian’s Glenn Greenwald Had the Scoop: Greenwald, an American columnist for the British newspaper, has a long history of challenging the surveillance state. Originally a self-described political agnostic who gave George W. Bush “the benefit of the doubt” over the invasion of Iraq, He wrote a scathing indictment of government overreach during the Bush administration in his 2006 book How Would a Patriot Act? During the Obama years he’s frequently criticized the President for infringing on civil liberties.